1. Field of the Invention
The invention relates generally to reciprocating compressors for use in an air conditioning system of a vehicle. More particularly, the invention relates to reciprocating compressors having an improved refrigerant suction efficiency.
2. Description of Related Art
Reciprocating compressors may include swash plate-type compressors, wobble plate-type compressors, or the like. Referring to FIG. 1, a known, wobble plate-type compressor 100 is described. Compressor 100 may comprise a cylinder block 1, a front housing 2, a rear housing 3, and a drive shaft 7. Drive shaft 7 may pass through the center of front housing 2 and the center of cylinder block 1. Drive shaft 7 also may be rotatably supported by front housing 2 and by cylinder block 1 via a pair of bearings 8a and 8b mounted in front housing 2 and cylinder block 1, respectively. A plurality of cylinder bores 5 may be formed within cylinder block 1 and also may be positioned equiangularly around an axis of drive shaft 7. Moreover, a piston 16 may be slidably positioned within each cylinder bore 5, such that pistons 16 reciprocate in a direction parallel to the axis of drive shaft 7.
Compressor 100 also may comprise a driving mechanism (not numbered). The driving mechanism may comprise drive shaft 7, a rotor 9, a crank chamber 4, and a swash plate 6. Specifically, rotor 9 is fixed to drive shaft 7, such that drive shaft 7 and rotor 9 rotate together. Crank chamber 4 is formed between front housing 2 and cylinder block 1, and swash plate 6 may be positioned inside crank chamber 4. Swash plate 6 may include a penetration hole 6c formed therethrough at a center portion of swash plate 6, and drive shaft 7 may extend through penetration hole 6c. Moreover, rotor 9 and swash plate 6 may be connected by a hinge mechanism 11 comprising a pin (not numbered) and an oblong hole (not numbered) formed through hinge mechanism 11. Hinge mechanism 11 allows the tilt angle of swash plate 6 to vary with respect to drive shaft 7. The drive mechanism also may comprise a substantially ring-shaped wobble plate 14 and a connection rod 15, and compressor 100 further may comprise a rotation prevention mechanism 17. Wobble plate 14 may be rotatably attached to swash plate 6 by a thrust bearing 12 and a radial bearing 13, and may engage rotation prevention mechanism 17. Wobble plate 14 also may be connected to piston 16 by rod 15 and a pair of ball joints 15a and 15b. Moreover, rotation prevention mechanism 17 may prevent wobble plate 14 from rotating about the axis of drive shaft 7. Nevertheless, ball joints 15a and 15b may allow wobble plate 14 to move back and forth in a wobbling motion.
Referring to FIGS. 1-3, compressor 100 also may comprise a valve plate 20 positioned between cylinder block 1 and rear housing 3, and a suction chamber 18 formed between rear housing 3 and valve plate 20. Valve plate 20 may include a suction hole 20a formed therethrough, which may allow suction chamber 18 to be in fluid communication with cylinder bore 5, such that a fluid, e.g., a refrigerant introduced from an external refrigerant circuit (not shown), may flow from suction chamber 18 to cylinder bore 5. Valve plate 20 may comprise a suction valve reed 21 formed on a side, e.g., the left side, of valve plate 20. Suction valve reed 21 regulates the fluid communication between suction chamber 18 and cylinder bore 5. Moreover, a limiting recess 23xe2x80x2 formed in cylinder block 1 and having a bottom surface 23b may limit the extent to which suction valve reed 21 may bend when fluid flows from suction chamber 18 to cylinder bore 5. Limiting recess 23xe2x80x2 comprises an arced segment formed symmetrically about a center axis (X) of suction valve reed 21, such that axis (X) also is the center axis of limiting recess 23xe2x80x2.
Compressor 100 further may comprise a discharge chamber 19, and valve plate 20 further may include a discharge hole 20b formed therethrough. Discharge hole 20b may allow cylinder bore 5 to be in fluid communication with discharge chamber 19, such that a fluid, e.g., a refrigerant, may flow from cylinder bore 5 to discharge chamber 19. The refrigerant subsequently may be discharged from discharge chamber 19 to the external refrigerant circuit. Valve plate 20 also may comprise a discharge valve reed 22 formed on a side, e.g., the right side, of valve plate 20. Specifically, discharge valve reed 22 is formed on the side opposite the side which suction valve reed 21 is formed. Discharge valve reed 22 regulates the fluid communication between cylinder bore 5 and discharge chamber 19. Moreover, a valve retainer 30 formed on discharge valve reed 22 may limit the extent to which discharge valve reed 22 may bend when fluid flows from cylinder bore 5 to discharge chamber 19.
Compressor 100 also may comprise an electromagnetic clutch 24. When electromagnetic clutch 24 is activated, an external driving force from an external driving source (not shown) is transmitted to drive shaft 7, such that drive shaft 7, rotor 9, and swash plate 6 rotate substantially simultaneously about the axis of drive shaft 7. Moreover, wobble plate 14 moves back and forth in a wobbling motion without rotating about the axis of drive shaft 7, such that only a direction of movement which is parallel to the axis of drive shaft 7 is transferred from wobble plate 14 to pistons 16. Consequently, each piston 16 reciprocates within its corresponding cylinder bore 5 and compresses the fluid, e.g., the refrigerant, which flows into cylinder bore 5 from suction chamber 18 via suction hole 20a. 
The reciprocation of piston 16 may be divided into a suction stroke and a discharge stroke. Specifically, during the suction stroke, discharge hole 20b may be closed by discharge valve reed 22, and during the discharge stroke, suction hole 20a may be closed by suction valve reed 21. Referring to FIGS. 2 and 3, during the suction stroke, the fluid generally flows in the direction of limiting recess 23xe2x80x2 as indicated by the arrow (L1). When the fluid approaches or reaches limiting recess 23xe2x80x2, the fluid deflects off a portion of limiting recess 23xe2x80x2 which intersects with center axis (X) and has a tangent line at the point of intersection which is substantially perpendicular to center axis (X) of suction valve reed 21. As such, when the fluid approaches or reaches limiting recess 23xe2x80x2, the direction of the flowing fluid changes by about 90xc2x0 and the fluid flows in the directions indicated by the arrow (L2). Nevertheless, because the direction of the flowing fluid changes by about 90xc2x0 when the fluid approaches or reaches limiting recess 23xe2x80x2, the speed of the fluid decreases and the fluid may become stagnant within limiting recess 23xe2x80x2. Consequently, during the suction stroke, the suction efficiency of the compressor may decrease.
Therefore, a need has arisen for refrigerant compressor which overcomes these and other shortcomings of the related art. A technical advantage of the present invention is that during the suction stroke, when a fluid approaches or reaches a limiting recess, the fluid may not become stagnant. Specifically, when the fluid approaches or reaches the limiting recess, the fluid may contact a portion of the limiting recess having a tangent line which forms an oblique angle relative to a center axis of a suction valve reed, i.e., an axis which is parallel to the direction of fluid flow. Consequently, when the fluid approaches or reaches the limiting recess, the fluid may deflect at an angle less than 90xc2x0, and the suction efficiency of the compressor may increase.
According to an embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. The limiting recess comprises at least one arced segment intersecting a center axis of the suction valve reed. Moreover, the portion of the at least one arced segment which intersects the center axis of the suction valve reed has a corresponding tangential line at the point of intersection which forms an oblique angle relative to the center axis of the suction valve reed.
According to another embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. Moreover, the limiting recess comprises a pair of arcs intersecting at or intersecting proximate to a center axis of the suction valve reed to form a ridge extending towards a center axis of the cylinder bore.
According to another embodiment of the present invention, a refrigerant compressor is described. The compressor comprises a front housing, a cylinder block, a rear housing, and a valve plate positioned between the cylinder block and the rear housing, in which the valve plate has a suction hole formed therethrough. The compressor also comprises a plurality of pistons each of which is slidably positioned within a corresponding cylinder bore, and a drive mechanism adapted to reciprocate each of the pistons within their corresponding cylinder bore. The compressor further comprises a suction chamber formed between the rear housing and the valve plate, and a suction valve reed formed on the valve plate which regulates the flow of a fluid through the suction hole. The compressor also comprises a limiting recess formed within an end of the cylinder block adapted to receive the suction valve reed. Moreover, the limiting recess comprises a pair of arcs intersecting at an axis offset from a center axis of the suction valve reed to form a ridge extending towards a center axis of the cylinder bore.
Other objects, features, and advantages will be apparent to persons of ordinary skill in the art in view of the following detailed description of the invention and the accompanying drawings.